Apparatus, systems and methods for enhancing IP multimedia subsystem service continuity

Abstract

Described herein are apparatus, systems and methods for enhancing Internet protocol (“IP”) multimedia subsystem service continuity. The methods including, at a user equipment (“UE”) connected to a first network using a first Radio Access Technology (“RAT”) and authorization information, connecting to a second network using a second RAT, transmitting a first registration attempt to an IP multimedia subsystem (“IMS”) associated with the second network, determining that the registration attempt with the IMS associated with the second network did not complete, clearing the authorization information, reconnecting to the first network and transmitting a second registration attempt to the IMS associated with the first network without the authorization information.

What is claimed is: 
     
       1. A method, comprising:
 at a user equipment (“UE”) connected to a first network using a first Radio Access Technology (“RAT”) and authorization information:
 connecting to a second network using a second RAT; 
 transmitting a first registration attempt to an internet protocol (“IP”) multimedia subsystem (“IMS”) associated with the second network; 
 determining that the registration attempt with the IMS associated with the second network did not complete; 
 clearing the authorization information; 
 reconnecting to the first network; and 
 transmitting a second registration attempt to the IMS associated with the first network without the authorization information. 
 
 
     
     
       2. The method of  claim 1 , wherein the first network is a Long Term Evolution (“LTE”) network. 
     
     
       3. The method of  claim 1 , wherein the second network is one of a Global System for Mobile Communications (“GSM”) network, a Universal Mobile Telecommunications System (“UMTS”) network, a Code Division Multiple Access (“CDMA”) network and a WiFi network. 
     
     
       4. The method of  claim 1 , wherein the registration attempt with the second network did not complete due to a failure to respond to a challenge from the second network. 
     
     
       5. The method of  claim 4 , wherein the challenge is provided to the UE in a Session Initiation Protocol (“SIP”) message. 
     
     
       6. The method of  claim 1 , wherein the first registration attempt with the second network did not complete due to one of the UE reconnecting with the first network or a timeout. 
     
     
       7. The method of  claim 1 , wherein the first registration attempt includes feature tags indicating at least one IMS service supported by the UE. 
     
     
       8. A user equipment (“UE”) connected to a first network using a first Radio Access Technology (“RAT”) and authorization information, comprising:
 a transceiver configured to enable the UE to establish a connection to the first network; and 
 a processor configured to:
 instruct the transceiver to connect to a second network using a second RAT, 
 instruct the transceiver to transmit a first registration attempt to an internet protocol (“IP”) multimedia subsystem (“IMS”) associated with the second network, 
 determine that the registration attempt with the IMS associated with the second network did not complete, 
 clear the authorization information, 
 instruct the transceiver to reconnect to the first network, and 
 instruct the transceiver to transmit a second registration attempt to the IMS associated with the first network without the authorization information. 
 
 
     
     
       9. The UE of  claim 8 , wherein the first network is a Long Term Evolution (“LTE”) network. 
     
     
       10. The UE of  claim 8 , wherein the second network is one of a Global System for Mobile Communications (“GSM”) network, a Universal Mobile Telecommunications System (“UMTS”) network, a Code Division Multiple Access (“CDMA”) network and a WiFi network. 
     
     
       11. The UE of  claim 8 , wherein the registration attempt with the second network did not complete due to a failure to respond to a challenge from the second network. 
     
     
       12. The UE of  claim 11 , wherein the challenge is provided to the UE in a Session Initiation Protocol (“SIP”) message. 
     
     
       13. The UE of  claim 8 , wherein the first registration attempt with the second network did not complete due to one of the UE reconnecting with the first network or a timeout. 
     
     
       14. The UE of  claim 8 , wherein the first registration attempt includes feature tags indicating at least one IMS service supported by the UE. 
     
     
       15. An integrated circuit, comprising:
 circuitry to connect to a first network using a first Radio Access Technology (“RAT”) and authorization information: 
 circuitry to connect to a second network using a second RAT; 
 circuitry to transmit a first registration attempt to an internet protocol (“IP”) multimedia subsystem (“IMS”) associated with the second network; 
 circuitry to determine that the registration attempt with the IMS associated with the second network did not complete; 
 circuitry to clear the authorization information; 
 circuitry to reconnect to the first network; and 
 circuitry to transmit a second registration attempt to the IMS associated with the first network without the authorization information. 
 
     
     
       16. The integrated circuit of  claim 15 , wherein the first network is a Long Term Evolution (“LTE”) network. 
     
     
       17. The integrated circuit of  claim 15 , wherein the second network is one of a Global System for Mobile Communications (“GSM”) network, a Universal Mobile Telecommunications System (“UMTS”) network, a Code Division Multiple Access (“CDMA”) network and a WiFi network. 
     
     
       18. The integrated circuit of  claim 15 , wherein the registration attempt with the second network did not complete due to a failure to respond to a challenge from the second network. 
     
     
       19. The integrated circuit of  claim 18 , wherein the challenge is provided to the UE in a Session Initiation Protocol (“SIP”) message. 
     
     
       20. The integrated circuit of  claim 15 , wherein the first registration attempt with the second network did not complete due to one of the UE reconnecting with the first network or a timeout.